Quantitative assessment of gastric tube perfusion during Ivor Lewis esophagectomy using indocyanine-green: results from the prospective interventional trial SPY Q-ICG PAS study

Background: Indocyanine green (ICG) fluorescence angiography is increasingly used to assess the vascularization of abdominal organs. In recent years, there has been a growing need to move beyond the subjectivity associated with its qualitative assessment by introducing objective quantification parameters (Q-ICG). The aim of this study is to identify a potential correlation between Q-ICG parameters and the risk of anastomotic leakage (AL) following Ivor Lewis esophagectomy for cancer. Methods: The SPY Q-ICG PAS study (NCT05489757) is a single-center, prospective, interventional trial conducted at San Raffaele Hospital in Milan between 2022 and 2023. In all patients undergoing Ivor Lewis esophagectomy for cancer, the following Q-ICG parameters were evaluated at the end of gastric conduit creation: maximum intensity (Fmax), half of Fmax intensity (F1), plateau intensity, intensity at the future anastomosis site, the time to reach F1 intensity (T1), the time to reach Fmax (time-to-peak, TTP), the ratio of TTP and T1 (TR), and Slope (Fmax/TTP). Results: Overall, 7 out of 76 patients (9.2%) experienced AL. No statistically significant differences were found between the AL and no-AL groups in terms of perioperative variables. Considering the Q-ICG parameters, the AL group exhibited longer T1 (17 ± 10 vs. 7 ± 2 s; p < 0,001), higher TR (0.71 ± 0.09 vs. 0.40 ± 0.10; p < 0,001), and lower Slope (3.94 ± 1.98 vs. 6.26 ± 2.79; p = 0.04). After multivariate analysis, T1 remained the only independent predictive factor for AL (OR = 5.613; p = 0.044). Moreover, a T1 of 9.50 s was identified as the best cut-off able to correctly classify patients in terms of AL in 89% of cases, with a sensitivity of 100% and a specificity of 88% (p < 0.001). Conclusions: Among all Q-ICG parameters, T1 resulted the best indicator for identifying patients at higher risk of developing postoperative AL following Ivor Lewis esophagectomy.